By now you’ve heard that yet another top Google exec has left for greener pastures at Facebook. This time it’s Sheryl Sandberg, who was some kind of bigshot running the ad business at Google or something like that. Best story on this I think was in today’s Wall Street Journal (see here) because they managed to get hold of Roger McNamee, this private equity dude who owns part of Palm and has been poaching Apple engineers left and right and then just smirking when I haul him down to Cupertino and shout at him. Turns out Roger is also some kind of mentor to Zuckerborg and has been encouraging the Z-Boy to poach Googlers.

Anyway this is not good news for Squirrel Boy and he knows it. Like, when the Journal puts a story like this on its front page, right in the middle, you know you’re going to get calls from your board members. But how can Google hope to hang on to these folks? The stock is topped out. Growth is slowing. The Borg is circling — clumsily, but circling nonetheless. Plus Google execs are all in huge demand because these little startups figure the Google whiz-kids must have some special magical knowledge because look at how well Google did right?

Maybe it doesn’t occur to the startup kids that Google’s top execs don’t have any special genius, they are just lucky bastards who landed in the right place at the right time. Or maybe the kiddies do know that and they simply don’t care. I hate to suggest that someone like Mark Zuckerberg might be entirely craven and cynical because gosh he looks like such a sweet fifteen-year-old kid and everything I’ve read about him makes him seem so nice. But maybe Z-Boy realizes that he needs a few Googlers on staff because he can play that up as a vote of confidence (“See, we must be on to something huge, look at all these Google execs jumping on board”).

The fact is, though Sheryl Sandberg might have some great operational skills, the reality is she doesn’t even need to ever show up at Facebook and she’d still be worth her weight in gold to Zuckerberg.

Here’s why. People like Sandberg who have made huge amounts of money, like hundreds of millions of dollars, can go anywhere and do anything. They choose their next job based on where they think they can make the biggest score. Her joining Facebook tells the world that a savvy Google exec, who could go anywhere and do anything, looked around and decided that the Next Big Thing is Facebook.

In other words, Sandberg’s value to Facebook arises not from her job skills but from her reputation as an investor. Sure, she’s not investing money; she’s investing her time and her name. But she’s investing nonetheless. She’s betting that this thing is going to pay off in a big way. And she will draw other investors behind her. It’s like when Warren Buffett invests in something. Everyone else jumps in too because they figure the Sage of Omaha knows something they don’t.

You have to remember what Facebook’s core business is about. It’s not about helping people stay in touch with friends or express themselves. It’s not about changing the world or creating an ecosystem for small apps makers. It’s not even about selling ads. Facebook is a vehicle through which a bunch of investors in the Valley hope to turn a small pile of money into a much bigger pile of money by selling shares in the public markets. That is Facebook’s core business. That is its raison d’etre as they say in Latin. This is a company created by, for and about venture capitalists. It’s not a company so much as it’s a narrative. A fable. A fairy tale.

Zuckerberg himself is pretty much incidental to the whole thing except that it makes the story a little better to have a boyish little Harvard dropout (cough Gates cough) in flip-flops and fleece jacket up on stage. (Not as CEO, mind you, because he’ll soon be giving that title to Sheryl Sandberg. Z-Boy will become Chief Innovation Visionary or Chief Strategy Architect or some other meaningless title which in English will translate into “World’s Luckiest Little Bastard.”)

Worse yet, right now Facebook is a friggin Ponzi scheme, with Facebook’s venture-funded apps partners making money primarily by selling ads to, um, Facebook’s other venture-funded apps partners. And voila, like that, everyone’s making money! Can you say shell game? Moreover, Facebook itself is being propped up and kept alive by the Borg, simply so it can serve as a thorn in Google’s side. And frankly the Borg will be happy to keep this thing alive and to help Z-Boy and his backers make obscene billions as long as Facebook saps energy from Google and distracts them and draws away their talent. Z-Boy, clever fellow that he is, is happy to serve as the Borg’s proxy in its war against Google, so long as he’s richly compensated, which he will be. He spotted a war between giants and cleverly turned that to his own advantage. Well played, kid.

Bottom line on the Sandberg hire is that what Zuckerberg and his advisers realize full well is this: IPOs usually boil down to one sentence that investment bankers can use when they call their clients. The one sentence Facebook would really like to have is this: “It’s the next Google.”

This is why Zuckerberg hired Sandberg — because ultimately what he’s trying to do is impress the saps in the public markets to whom he’ll soon be trying to flog shares. Sandberg brings huge street cred in that regard.

Well it’s great news for Facebook and bad news for Google. Everyone out here has seen this coming for months. Which is why last November we crafted Eric Schmidt’s Serenity Prayer. Makes good reading today in light of the Sandberg defection.